Data transmission method, apparatus, and system

ABSTRACT

This application discloses a data transmission method, apparatus, and system. The method includes: generating a to-be-sent bit sequence, where the to-be-sent bit sequence includes one or more bits in a bit sequence having a length of (N−M), where N is a length of a mother code for polar encoding, M is a length of encoded bits obtained after rate matching is performed on a bit sequence having a length of N, N is m raised to the power of an integer, m is a positive integer greater than 1, M is a positive integer, and N&lt;M; and sending the generated bit sequence. A corresponding apparatus and system are further disclosed. In this application, in this data transmission solution, an additional coding gain is generated during decoding, so that a decoding FER is reduced, and decoding performance is improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2019/071823, filed on Jan. 15, 2019, which claims priority toChinese Patent Application No. 201810041373.1, filed on Jan. 16, 2018.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the field of communications technologies,and in particular, to a data transmission method, apparatus, and system.

BACKGROUND

Rapid evolution of wireless communication indicates that a future fifthgeneration (5G) communications system will present some new features.The most typical three communications scenarios include enhanced mobilebroadband (eMBB), massive machine type communications (mMTC), andultra-reliable and low latency communications (URLLC). Requirements ofthe communications scenarios pose new challenges to existing long termevolution (LTE) technologies. Channel coding, as a most basic radioaccess technology, is an important research object to meet a 5Gcommunications requirement. A polar code is the first good code that haslow encoding and decoding complexity and that theoretically proves thata Shannon capacity can be obtained.

A typical scenario in 5G is communication that has a relatively highreliability requirement but is insensitive to a delay. A most commonlyused method is to improve communications reliability by using a hybridautomatic repeat request (HARQ), so that a higher link throughput isachieved.

However, in the prior art, in a polar code HARQ scheme, a same sequenceis repeatedly sent during each retransmission until an acknowledgment(ACK) feedback signal is received, and a receive end combines all softinformation received each time for decoding. However, decodingperformance of directly retransmitting an original information bit isrelatively poor, and a decoding frame error rate (FER) is relativelyhigh.

Therefore, a data transmission solution in which a particular codinggain can be generated needs to be provided urgently.

SUMMARY

This application provides a retransmission method and a communicationsapparatus, so that in this data transmission solution, an additionalcoding gain is generated during decoding. Therefore, a decoding FER isreduced, and decoding performance is improved.

According to one aspect, a data transmission method is provided, andincludes: generating a to-be-sent bit sequence, where the to-be-sent bitsequence includes one or more bits in a bit sequence having a length of(N−M), where N is a length of a mother code for polar encoding, M is alength of encoded bits obtained after rate matching is performed on abit sequence having a length of N, N is m raised to the power of aninteger, m is a positive integer greater than 1, M is a positiveinteger, and N<M; and sending the generated bit sequence. In thisaspect, in this data transmission solution, an additional coding gain isgenerated during decoding, so that a decoding FER is reduced, anddecoding performance is improved.

In one embodiment, the to-be-sent bit sequence further includes one ormore bits in the bit sequence having the length of N.

In one embodiment, when m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t),a length of the to-be-sent bit sequence is min (m{circumflex over( )}(ceil (log_(m)M)+1), Nmax), where P_(t) is a threshold of a quantityof punctured bits, and Nmax is a maximum length of the mother code.

In one embodiment, when N meets the following conditions: N/2−M≤P_(t),and N−M≥P_(t), a length of the to-be-sent bit sequence is min(m{circumflex over ( )}(ceil (log_(m)M)+1), Nmax), where P_(t) is athreshold of a quantity of punctured bits, and Nmax is a maximum lengthof the mother code.

According to another aspect, a data transmission apparatus is provided,and includes: a processing module, configured to generate a to-be-sentbit sequence, where the to-be-sent bit sequence includes one or morebits in a bit sequence having a length of (N−M), where N is a length ofa mother code for polar encoding, M is a length of encoded bits obtainedafter rate matching is performed on a bit sequence having a length of N,N is m raised to the power of an integer, m is a positive integergreater than 1, M is a positive integer, and N<M; and a sending module,configured to send the generated bit sequence.

In one embodiment, the to-be-sent bit sequence further includes one ormore bits in the bit sequence having the length of N.

In one embodiment, when m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t),a length of the to-be-sent bit sequence is min (m{circumflex over( )}(ceil (log_(m)M)+1), Nmax), where P_(t) is a threshold of a quantityof punctured bits, and Nmax is a maximum length of the mother code.

In one embodiment, when N meets the following conditions: N/2−M≤P_(t),and N−M≥P_(t), a length of the to-be-sent bit sequence is min(m{circumflex over ( )}(ceil (log_(m)M)+1), Nmax), where P_(t) is athreshold of a quantity of punctured bits, and Nmax is a maximum lengthof the mother code.

In one embodiment, the apparatus is a network device or a terminaldevice.

According to still another aspect, an encoding apparatus is provided,and includes: a processor, and the processor is configured to generate ato-be-sent bit sequence, where the to-be-sent bit sequence includes oneor more bits in a bit sequence having a length of (N−M), where N is alength of a mother code for polar encoding, M is a length of encodedbits obtained after rate matching is performed on a bit sequence havinga length of N, N is m raised to the power of an integer, m is a positiveinteger greater than 1, M is a positive integer, and N<M.

In one embodiment, the to-be-sent bit sequence further includes one ormore bits in the bit sequence having the length of N.

In one embodiment, when m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t),a length of the to-be-sent bit sequence is min (m{circumflex over( )}(ceil (log_(m)M)+1), Nmax), where P_(t) is a threshold of a quantityof punctured bits, and Nmax is a maximum length of the mother code.

In one embodiment, when N meets the following conditions: N/2−M≤P_(t),and N−M≥P_(t), a length of the to-be-sent bit sequence is min(m{circumflex over ( )}(ceil (log_(m)M)+1), Nmax), where P_(t) is athreshold of a quantity of punctured bits, and Nmax is a maximum lengthof the mother code.

In one embodiment, the apparatus further includes a memory, and thememory is configured to store a program instruction.

In one embodiment, the apparatus is a network device or a terminaldevice.

According to still another aspect, a data transmission apparatus isprovided, and includes: an input interface circuit, configured to obtaina bit sequence when a length of a mother code is N; a logic circuit,configured to generate a to-be-sent bit sequence, where the to-be-sentbit sequence includes one or more bits in a bit sequence having a lengthof (N−M), where N is a length of a mother code for polar encoding, M isa length of encoded bits obtained after rate matching is performed on abit sequence having a length of N, N is m raised to the power of aninteger, m is a positive integer greater than 1, M is a positiveinteger, and N<M; and an output interface circuit, configured to outputthe to-be-sent bit sequence.

In one embodiment, the to-be-sent bit sequence further includes one ormore bits in the bit sequence having the length of N.

In one embodiment, when m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t),a length of the to-be-sent bit sequence is min (m{circumflex over( )}(ceil (log_(m)M)+1), Nmax), where P_(t) is a threshold of a quantityof punctured bits, and Nmax is a maximum length of the mother code.

In one embodiment, when N meets the following conditions: N/2−M≤P_(t),and N−M≥P_(t), a length of the to-be-sent bit sequence is min(m{circumflex over ( )}(ceil (log_(m)M)+1), Nmax), where P_(t) is athreshold of a quantity of punctured bits, and Nmax is a maximum lengthof the mother code.

In one embodiment, the apparatus is a network device or a terminaldevice.

According to still another aspect, a data transmission system isprovided, and the data transmission system includes a network device anda terminal device, where the network device includes the foregoing datatransmission apparatuses; and/or the terminal device includes theforegoing data transmission apparatuses.

According to still another aspect, a chip is provided, and includes: aprocessor, and the processor is configured to generate a to-be-sent bitsequence, where the to-be-sent bit sequence includes one or more bits ina bit sequence having a length of (N−M), where N is a length of a mothercode for polar encoding, M is a length of encoded bits obtained afterrate matching is performed on a bit sequence having a length of N, N ism raised to the power of an integer, m is a positive integer greaterthan 1, M is a positive integer, and N<M.

In one embodiment, the chip further includes a memory, configured tostore a program.

According to still another aspect, a readable storage medium isprovided, and includes a readable storage medium and a computer program,where the computer program is used to implement the encoding methodaccording to any one of the foregoing aspects.

According to still another aspect, a program product is provided, wherethe program product includes a computer program, the computer program isstored in a readable storage medium, at least one processor of anencoding apparatus may read the computer program from the readablestorage medium, and the at least one processor executes the computerprogram, to enable the encoding apparatus to implement the encodingmethod according to any one of the foregoing aspects.

According to still another aspect, a decoding method is provided, andincludes: receiving soft information corresponding to a bit sequence,where the soft information includes soft information corresponding toone or more bits in a bit sequence having a length of (N−M), where N isa length of a mother code for polar encoding, M is a length of encodedbits obtained after rate matching is performed on a bit sequence havinga length of N, N is m raised to the power of an integer, m is a positiveinteger greater than 1, M is a positive integer, and N<M; and combiningthe soft information for decoding, to obtain decoded bits.

In one embodiment, the soft information further includes one or morebits in the bit sequence having the length of N.

According to still another aspect, a decoding apparatus is provided, andincludes: a receiving module, configured to receive soft informationcorresponding to a bit sequence, where the soft information includessoft information corresponding to one or more bits in a bit sequencehaving a length of (N−M), where N is a length of a mother code for polarencoding, M is a length of encoded bits obtained after rate matching isperformed on a bit sequence having a length of N, N is m raised to thepower of an integer, m is a positive integer greater than 1, M is apositive integer, and N<M; and a processing module, configured tocombine the soft information for decoding, to obtain decoded bits.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of thisapplication or in the background more clearly, the following describesthe accompanying drawings for describing the embodiments of thisapplication or the background.

FIG. 1 is a schematic diagram of channel coding in a communicationslink;

FIG. 2 is a schematic diagram of HARQ transmission;

FIG. 3 is a schematic diagram of a communications system according to anembodiment of this application;

FIG. 4 is a schematic flowchart of a data transmission method accordingto an embodiment of this application;

FIG. 5 is a schematic diagram of performance comparison between asolution of this application and an existing retransmission solution;

FIG. 6 is a schematic structural diagram of a data transmissionapparatus according to an embodiment of this application;

FIG. 7 is a schematic structural diagram of an encoding apparatusaccording to an embodiment of this application;

FIG. 8 is a schematic structural diagram of another encoding apparatusaccording to an embodiment of this application;

FIG. 9 is a schematic flowchart of a decoding method according to anembodiment of this application;

FIG. 10 is a schematic diagram of combining soft information received bya receive end;

FIG. 11 is a schematic structural diagram of a decoding apparatusaccording to an embodiment of this application;

FIG. 12 is a schematic structural diagram of another decoding apparatusaccording to an embodiment of this application;

FIG. 13 is a schematic structural diagram of still another encodingapparatus according to an embodiment of this application;

FIG. 14 is a schematic structural diagram of a network device accordingto an embodiment of this application; and

FIG. 15 is a schematic structural diagram of a terminal device accordingto an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following describes the embodiments of this application withreference to the accompanying drawings in the embodiments of thisapplication.

FIG. 1 is a schematic diagram of channel coding in a communicationslink. A transmit end obtains a signal by performing source coding,channel coding, rate matching, and digital modulation on information,and sends the signal by using a channel. A receive end receives thesignal by using the channel, and finally restores the information byperforming digital demodulation, rate de-matching, channel decoding, andsource decoding on the signal.

An embodiment of this application provides a data transmission solution.A retransmission manner in the data transmission solution may be an HARQtransmission manner, or may be another retransmission manner. Thefollowing mainly describes an HARQ transmission mechanism.

In the HARQ transmission mechanism, channel coding and automatic repeatrequest technologies are combined. A small-scale error that occursduring transmission can be directly corrected through channel coding. Atransmission error that cannot be corrected by using a channel codingerror correction capability is notified by the receive end to thetransmit end by using a feedback link, to request resending the message.

In a schematic diagram of HARQ transmission shown in FIG. 2, if decodingfails at a receive end (for example, a cyclic redundancy check (CRC)fails), a negative acknowledgment (NACK) message is transmitted to atransmit end by using a feedback link, and the transmit end sends newdata. The process continues until the receive end sends anacknowledgment (ACK) message to the transmit end for notifying thetransmit end that decoding is correct, so that transmission of aninformation block is completed.

The transmit end sends the new data to the receive end. The new dataherein may include one or more bits in a bit sequence having a length of(N−M), where N is a length of a mother code for polar encoding, M is alength of encoded bits obtained after rate matching is performed on abit sequence having a length of N, N is m raised to the power of aninteger, m is a positive integer greater than 1, M is a positiveinteger, and N<M. Based on the data, by using an additional coding gain,the receive end may reduce a decoding FER and improve decodingperformance.

In addition, in the data transmission solution of this application, aplurality of types of codes may be used for encoding and decoding. Thefollowing mainly and briefly describes encoding and decoding of a polarcode.

The polar code is a linear block code. A generator matrix of the polarcode is G_(N), and an encoding process of the polar code is x₁ ^(N)=u₁^(N)G_(N), where u₁ ^(N)=(u₁,u₂,K,u_(N)) is a binary row vector having alength (that is, a code length) of N. G_(N) is a matrix of N×N, andG_(N)=F₂ ^(⊗(log) ² ^((N))), where F₂ [₁ ¹ ₁ ⁰] ^(⊗(log) ² ^((N))) isdefined as a Kronecker product of log₂N matrices F_(Z). Both additionand multiplication operations mentioned above are addition andmultiplication operations in a binary Galois field.

In the encoding process of the polar code, some bits of u₁ ^(N) are usedto carry information, and are referred to as information bits, and a setof indexes of the information bits is denoted as A; and some other bitsof u₁ ^(N) are set to fixed values on which the receive end and thetransmit end agree in advance, and are referred to as constant bits, anda set of indexes of the constant bits is represented by using acomplementary set A^(c) of A. An information bit sequence number set Ais selected based on the following method. A polar channel errorprobability P_(e) ^((i)) corresponding to a bit having a sequence numberi may first be obtained based on a constructing algorithm of the polarcode, and K sequence numbers having smallest P_(e) ^((i)) values arethen selected to construct the set A. Alternatively, a reliabilitysorting sequence that meets an inclusion relationship may be storedoffline, and K polar channel sequence numbers having highest reliabilityin a current mother code are read from the sequence based on K and N, toconstruct the set A.

A most basic decoding method of the polar code is a successivecancellation (SC) decoding method. However, in the algorithm,performance is not ideal when the code length is limited. A successivecancellation list (SCL) decoding algorithm subsequently proposedimproves decoding performance of a short code by using a method oftransverse path extension and CRC check selection. The decodingalgorithm can be used to obtain, when the polar code, a Turbo code, anda low-density parity-check code have equivalent decoding complexity,frame error rate (FER) performance that is better than frame error rateperformance of the Turbo code and the low-density parity-check (LDPC)code.

FIG. 3 is a schematic diagram of a communications system according to anembodiment of this application. The communications system may include atleast one network device 100 (only one network device is shown) and oneor more terminal devices 200 connected to the network device 100. Inthis application, if a transmit end device may be a terminal device, areceive end device may be a network device. Alternatively, if a transmitend device may be a network device, a receive end device may be aterminal device.

The network device 100 may be a device that can communicate with theterminal device 200. The network device 100 may be any device having awireless transceiver function. The device includes but is not limited toa base station (for example, a NodeB, an evolved NodeB (eNodeB), a basestation in the fifth generation (5G) communications system, a basestation or a network device in a future communications system, an accessnode in a Wi-Fi system, a wireless relay node, or a wireless backhaulnode), or the like. Alternatively, the network device 100 may be a radiocontroller in a cloud radio access network (CRAN) scenario.Alternatively, the network device 100 may be a network device in a 5Gnetwork or a network device in a future evolved network, or may be awearable device, a vehicle-mounted device, or the like. Alternatively,the network device 100 may be a small cell, a transmission node(transmission reference point (TRP)), or the like. Certainly, thisapplication is not limited thereto.

The terminal device 200 is a device having a wireless transceiverfunction. The device may be deployed on the land, including an indoor oroutdoor device, a handheld device, a wearable device, or avehicle-mounted device. The device may alternatively be deployed on thewater (for example, on a ship). The device may alternatively be deployedover the air (for example, over an aircraft, a balloon, or a satellite).The terminal device may be a mobile phone (mobile phone), a tablet(Pad), a computer having a wireless transceiver function, a virtualreality (VR) terminal device, an augmented reality (AR) terminal device,a wireless terminal in industrial control, a wireless terminal in selfdriving, a wireless terminal in telemedicine (remote medical), awireless terminal in a smart grid, a wireless terminal fortransportation safety, a wireless terminal in a smart city), a wirelessterminal in a smart home, or the like. An application scenario is notlimited in this embodiment of this application. The terminal devicesometimes may alternatively be referred to as user equipment (UE), anaccess terminal device, a UE unit, a UE station, a mobile station, amobile console, a remote station, a remote terminal device, a mobiledevice, a UE terminal device, a terminal, a terminal device, a wirelesscommunications device, a UE agent, a UE apparatus, or the like.

It should be noted that the terms “system” and “network” may be usedinterchangeably in the embodiments of this application. “A plurality of”means two or more. In view of this, “a plurality of” may also beunderstood as “at least two” in the embodiments of this application. Theterm “and/or” describes an association relationship for describingassociated objects and represents that three relationships may exist.For example, A and/or B may represent the following three cases: Only Aexists, both A and B exist, and only B exists. In addition, unlessotherwise stated, the character “/” generally indicates an “or”relationship between the associated objects.

The embodiments of this application provide a data transmission methodand apparatus. In the data transmission solution, an additional codinggain is generated during decoding, so that a decoding FER is reduced,and decoding performance is improved.

FIG. 4 is a schematic flowchart of a data transmission method accordingto an embodiment of this application. The method includes the followingoperations.

S401: Generate a to-be-sent bit sequence, where the to-be-sent bitsequence includes one or more bits in a bit sequence having a length of(N−M), where N is a length of a mother code for polar encoding, M is alength of encoded bits obtained after rate matching is performed on abit sequence having a length of N, N is m raised to the power of aninteger, m is a positive integer greater than 1, M is a positiveinteger, and N<M.

S402: Send the generated bit sequence.

In this embodiment, polar encoding is first performed on the mother codehaving the length of N, to obtain that the length of the encoded bitsobtained after rate matching is performed is M. The M encoded bits and(N−M) bits are sequentially sent. In one embodiment, the M encoded bitsare initially transmitted, and then one or more bits in the (N−M) bitsare retransmitted, or one or more bits in the M initially transmittedbits may be retransmitted. The M encoded bits and the (N−M) bits may bestored in a buffer, and the bits in the buffer are sequentially read forsending until a length of bits sent during initial transmission or alength of bits sent during retransmission is reached.

For example, m=2, that is, the length of the mother code is 2 raised tothe power of an integer. Certainly, m may alternatively be anothervalue.

Further, interleaving and rate matching are performed on the mothercode, to obtain the M encoded bits.

Further, the to-be-sent bit sequence further includes one or more bitsin the bit sequence having the length of N. In this embodiment, beforeor after the bit sequence having the length of (N−M) is sent, one ormore bits in a bit sequence having the length of N are further sent.

In this embodiment, encoding and decoding of a polar code is used as anexample to describe the data transmission solution. In one embodiment,

before encoded, the polar code is first constructed based on an actualparameter (including a length N of a to-be-encoded sequence u₁ ^(N), alength K of to-be-transmitted information bits, or the like), and apreferred polar channel is selected through online calculation or tablereading, to generate an information bit sequence number set A. Someother bits are set to fixed values on which a receive end and a transmitend agree in advance, and are referred to as constant bits, and a set ofindexes of the constant bits is represented by using a complementary setA^(c) of A.

In this embodiment, a value of the length N of the mother code of thepolar code needs to be designed.

In one embodiment, the value of the length N of the mother code isdetermined. When m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t), thevalue of the length N of the mother code is min (m{circumflex over( )}(ceil (log_(m)M)+1), Nmax), where “m{circumflex over ( )}ceil(log_(m)M)” represents an encoding length that is closest to M and thatis greater than or equal to M, P_(t) represents a threshold of aquantity of punctured bits, and N_(max) is a maximum length that is ofthe mother code and that is preset in a polar code system. Whenm{circumflex over ( )}(ceil (log_(m)M)+1)<N_(max), the value of thelength N of the mother code is m{circumflex over ( )}(ceil(log_(m)M)+1); when m{circumflex over ( )}(ceil (log_(m)M)+1)>N_(max),the value of the length N of the mother code is N_(max); or whenm{circumflex over ( )}(ceil (log_(m)M)+1)−N_(max), the value of thelength N of the mother code is m{circumflex over ( )}(ceil(log_(m)M)+1), or N_(max), P_(t) is a threshold of a quantity ofpunctured bits, and Nmax is a maximum length that is of the mother codeand that is set in the system. In one embodiment, when the length of themother code is designed, it is considered that the length of the mothercode is selected as long as possible, so that (N−M) bits can begenerated as many as possible for selection. Such consideration isapplied to a retransmission scenario. During retransmission, the (N−M)bits are used for retransmission, to generate a coding gain. By usingthe additional coding gain during decoding, a decoding FER is reducedand decoding performance is improved.

In one embodiment, the length N of the mother code may be designed tomeet the following conditions: N/2−M≤P_(t), and N−M≥P_(t), where P_(t)is a threshold of a quantity of punctured bits. In one embodiment, whenthe length of the mother code is designed, the to-be-sent bit includesbits of a quantity for selection, where the quantity is greater than orequal to the threshold. Such a design particularly is applied to anapplication scenario of retransmission. The length N that is of themother code and that meets the foregoing condition is selected, so that(N−M) bits may be generated as many as possible for retransmission.Therefore, a coding gain is generated. By using the additional codinggain during decoding, a decoding FER is reduced and decoding performanceis improved.

In one embodiment, a threshold P_(t) of a quantity of punctured bits isdetermined based on at least one of the following parameters: a coderate R, a code length M, and a rate matching manner including ashortening or puncturing manner. For example, P_(t) is determined basedon the formula P_(t)=m{circumflex over ( )}ceil (log_(m)M)/K, where K isa positive integer greater than or equal to 2. P_(t) may alternativelybe a fixed value on which both a receive end and a transmit end agree,for example, 10 or 20.

Polar encoding then is performed on to-be-encoded bits. In oneembodiment, a mother code x₁ ^(N) (Seq. 0) needs to be obtained, basedon A, A^(c), and a to-be-encoded sequence u₁ ^(N), by multiplying u₁^(N) by an encoding matrix G.

Further, the embodiment further includes the following operation:Interleaving and rate matching are performed on the bit sequence havingthe length of N, to obtain encoded bits obtained after rate matching isperformed and (N−M) unsent bits, where the (N−M) unsent bits may also beconsidered as encoded bits that are punctured. In one embodiment,interleaving and rate matching are performed on the Seq. 0, to obtain abit sequence v₁ ^(M) (Seq. 1).

In one process, the mother code is interleaved in a specifiedinterleaving manner. The specified interleaving manner includes at leastone of the following manners: interleaving is performed in a bit order,interleaving is performed in a bit reversal order, and groupinterleaving. During the process, the mother code may be interleaved ina rate matching manner, and the interleaved mother code is stored in acircular buffer. During each retransmission, starting from a next bitafter previous retransmission is finished, bits in the mother code maybe sequentially read until a length of bits that are sent is reached.

For example, interleaving is performed in a predetermined rate matchinginterleaving manner to obtain the sequence Seq. 1, and interleaved bitsare arranged in a sequence that is based on a rate matching priorityorder. A particular interleaving manner may be in a bit order, may be ina bit reversal order, or may be in a predetermined group interleavingmanner. For example, codewords of the mother code are evenly dividedinto 32 groups, which are respectively labeled as 1, 2, . . . , 31. Eachgroup is arranged in a specific order, to obtain an interleaved bitsequence. The interleaved sequence, namely, a relative position order ofall groups, is [0 1 2 4 3 5 6 7 8 16 9 17 10 18 11 19 12 20 13 21 14 2215 23 24 25 26 28 27 29 30 31].

In the interleaved bit sequence, a bit priority of the interleaved bitsequence is corresponding to a rate matching priority. For example, ratematching is preferentially performed on a bit that ranks higher or lowerin the interleaved bit sequence.

Bits in the sequence 1 are sequentially placed in the circular bufferfor data transmission, for example, for initial transmission andretransmission of data.

Bits are selected from the Seq. 0 and are added to a to-be-transmittedbit sequence Seq. 2, to generate a to-be-sent bit sequence, and bits inthe to-be-sent bit sequences are sequentially stored in the circularbuffer. The selected encoded bits may be one or more bits in the bitsequence having the length of N, may be one or more bits in the bitsequence having the length of (N−M), or may be one or more bits in thebit sequence having the length of N and one or more bits in the bitsequence having the length of (N−M).

The bits in the mother code having the length of N are stored in thebuffer in a specific order. Starting from a next bit after sending thesequence is finished, the encoded bits in the to-be-transmitted bitsequence Seq. 2 are sequentially read, to send the to-be-transmitted bitsequence.

In a possible manner, if a starting point and a reading direction of thecircular buffer are consistent with a starting point and a readingdirection of the interleaved sequence, the first P bits are skipped toread remaining M bits. In another retransmission application scenario,when a receive end receives a retransmitted message, the receive endsends to-be-transmitted bits, where the to-be-transmitted bits arelocated after a last bit that is sent previously, and theto-be-transmitted bits are sequentially sent starting from a next bitafter last sending is finished.

By using the HARQ process shown in FIG. 2 as an example, the transmitend may first perform encoding on the entire bit sequence having thelength of N. Then, one or more bits in the bit sequence having thelength of N are sent for the first time, and the receive end performschannel decoding and performs a CRC check. If the CRC fails, an NACK isfed back. The transmit end sends the to-be-sent bit sequence for thesecond time, where the to-be-sent bit sequence includes one or more bitsin the bit sequence having the length of (N−M), and may further send oneor more bits in the bit sent for the first time. The receive endattempts to combine received signals of the first two times fordecoding. If the CRC succeeds, an ACK is fed back; and if the CRC stillfails, the NACK is fed back. The transmit end sends one or more bits inthe (N−M) bits for a t^(th) time, or may send one or more bits in bitssent for the first t−1 times. The receive end combines received signalsof the first t times for decoding (t is an integer greater than 2).After t^(th) sending, if the transmit end receives the ACK, it isdeclared that the sending succeeds; and if the NACK is received and theNACK has been sent for a maximum quantity of times, it is declared thatthe sending fails.

It should be noted that, a communications system uses repeatedretransmission at some code length bit rates, and still uses incrementalredundancy (IR) transmission at some code length bit rates. Therefore,the solution in this embodiment may be usually used in a hybridautomatic repeat request-incremental redundancy (HARQ-IR) mode.Therefore, in one embodiment, whether a punctured bit is included in theretransmission may alternatively be determined based on at least oneparameter in a code length, a code rate, or a rate matching manner. Ifthe punctured bit is included in the retransmission, the solution inthis embodiment is used.

In this application, the to-be-sent sequence having a bit priority isgenerated, so that a coding gain of the polar code is fully used, andaccuracy on a decoding side is improved.

FIG. 5 is a performance comparison curve of four times of transmissionbetween a solution of this application and existing retransmissionsolutions. For ease of comparison, the solution of this application isdenoted as IR1; the solution in which repeated sending is performed isdenoted as CC; and a solution is denoted as IR2. In the solution denotedas IR2, during each retransmission, a transmit end selects, based onreliability corresponding to each information bit in a set, aninformation bit having relatively low reliability from the set, todirectly perform retransmission. A horizontal coordinate Es/N0represents a signal-to-noise ratio, and a vertical coordinate representsa block error rate (BLER)/packet loss rate. It can be clearly learnedfrom the figure that, because performance during the firstretransmission during which an IR2 technology is used is not ideal,subsequent two times of retransmission does not need to be compared withthis solution. Set parameters include an additive white Gaussian noise(AWGN) channel and binary phase shift keying (BPSK) modulation. A codelength of a mother code is 512, and a length of a sequence sent eachtime is 412. During the second transmission, the third transmission, andthe fourth transmission having same signal-to-noise ratios, a packetloss rate in the IR1 solution is lower than that in the CC solution.Therefore, it can be learned that in the CC solution, because same bitsare sent during each retransmission, a generated coding gain isrelatively small. However, in the solutions of this application, otherthan encoded bits for initial transmission, other encoded bits in themother code are sent. Therefore, an additional coding gain is generatedduring decoding, so that a decoding FER is reduced, and decodingperformance is improved.

According to a data transmission method provided in this embodiment ofthis application, in this data transmission solution, the additionalcoding gain is generated during decoding, so that the decoding FER isreduced, and the decoding performance is improved.

Based on an inventive concept the same as that of the data transmissionmethod shown in FIG. 4, as shown in FIG. 6, an embodiment of thisapplication further provides a data transmission apparatus 6000. Thedata transmission apparatus 6000 is configured to perform the datatransmission method shown in FIG. 4. The apparatus may be applicable tothe communications system shown in FIG. 3. In one embodiment, the datatransmission apparatus 6000 includes:

a processing module 61, configured to generate a to-be-sent bitsequence, where the to-be-sent bit sequence includes one or more bits ina bit sequence having a length of (N−M), where N is a length of a mothercode for polar encoding, M is a length of encoded bits obtained afterrate matching is performed on a bit sequence having a length of N, N ism raised to the power of an integer, m is a positive integer greaterthan 1, M is a positive integer, and N<M; and

a sending module 62, configured to send the generated bit sequence.

In this embodiment, polar encoding is first performed on the mother codehaving the length of N, to obtain that the length of the encoded bitsobtained after rate matching is performed is M. The M encoded bits and(N−M) bits are sequentially sent. In one embodiment, the M encoded bitsare initially transmitted, and then one or more bits in the (N−M) bitsare retransmitted, or one or more bits in the M initially transmittedbits may be retransmitted. The M encoded bits and the (N−M) bits may bestored in a buffer, and the bits in the buffer are sequentially read forsending until a length of bits sent during initial transmission or alength of bits sent during retransmission is reached.

For example, m=2, that is, the length of the mother code is 2 raised tothe power of an integer. Certainly, m may alternatively be anothervalue.

Further, interleaving and rate matching are performed on the mothercode, to obtain the M encoded bits.

In one embodiment, the data transmission apparatus 6000 further includesa constructing module 63 and an encoding module 64.

The constructing module 63 is configured to construct an information bitsequence number set based on a length of a to-be-encoded sequence and alength of to-be-transmitted information bits.

Before encoded, a polar code is first constructed based on an actualparameter (including the length N of the to-be-encoded sequence u₁ ^(N),the length K of the to-be-transmitted information bits, or the like),and a preferred polar channel is selected through online calculation ortable reading, to generate an information bit sequence number set A.Some other bits are set to fixed values on which a receive end and atransmit end agree in advance, and are referred to as constant bits, anda set of indexes of the constant bits is represented by using acomplementary set A^(c) of A.

The encoding module 64 is configured to encode to-be-encoded bits.

Polar encoding is performed on the to-be-encoded bits. In oneembodiment, a mother code x₁ ^(N) (Seq. 0) needs to be obtained, basedon A, A^(c), and a to-be-encoded sequence u₁ ^(N), by multiplying u₁^(N) by an encoding matrix G.

Further, the to-be-sent bit sequence further includes:

one or more bits in the bit sequence having the length of N.

Further, when m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t), a value ofthe length N of the mother code is min (m{circumflex over ( )}(ceil(log_(m)M)+1), N_(max)), where “m{circumflex over ( )}ceil (log_(m)M)”represents an encoding length that is closest to M and that is greaterthan or equal to M, P_(t) represents a threshold of a quantity ofpunctured bits, and N_(max) is a maximum length that is of the mothercode and that is preset in a polar code system. When m{circumflex over( )}(ceil (log_(m)M)+1)<N_(max), the value of the length N of the mothercode is m{circumflex over ( )}(ceil (log_(m)M)+1); when m{circumflexover ( )}(ceil (log_(m)M)+1)>N_(max), the value of the length N of themother code is N_(max); or when m{circumflex over ( )}(ceil(log_(m)M)+1)−N_(max), the value of the length N of the mother code ism{circumflex over ( )}(ceil (log_(m)M)+1), or N_(max). P_(t) is athreshold of a quantity of punctured bits, and N_(max) is a maximumlength that is of the mother code and that is set in the system. In thisembodiment, when the length of the mother code is designed, it is moreconsidered that the length of the mother code is selected as long aspossible, so that (N−M) bits can be generated as many as possible forselection. Such consideration is applied to a retransmission scenario.During retransmission, the (N−M) bits are used for retransmission, togenerate a coding gain. By using the additional coding gain duringdecoding, a decoding FER is reduced and decoding performance isimproved. Further, the length N of the mother code should be designed tomeet the following conditions: N/2−M≤P_(t), and N−M≥P_(t), where P_(t)is the threshold of a quantity of punctured bits. In this embodiment,when the length of the mother code is designed, the to-be-sent bitincludes bits of a quantity for selection, where the quantity is greaterthan or equal to the threshold. Such a design particularly is applied toan application scenario of retransmission. The length N that is of themother code and that meets the foregoing condition is selected, so that(N−M) bits may be generated as many as possible for retransmission.Therefore, a coding gain is generated. By using the additional codinggain during decoding, a decoding FER is reduced and decoding performanceis improved.

Further, a threshold P_(t) of a quantity of punctured bits is determinedbased on at least one of the following parameters: a code rate R, a codelength M, and a rate matching manner including a shortening orpuncturing manner. For example, P_(t) is determined based on the formulaP_(t)=m{circumflex over ( )}ceil (log_(m)M)/K, where K is a positiveinteger greater than or equal to 2. P_(t) may alternatively be a fixedvalue on which both a receive end and a transmit end agree, for example,10 or 20.

Further, the apparatus is a network device or a terminal device.

According to a data transmission apparatus provided in this embodimentof this application, in this data transmission solution, the additionalcoding gain is generated during decoding, so that the decoding FER isreduced, and the decoding performance is improved.

An embodiment of this application further provides a data transmissionsystem, and the data transmission system includes the network device andthe terminal device, where the network device/terminal device includesthe foregoing data transmission apparatus.

Based on the data transmission method shown in FIG. 4, as shown in FIG.7, an embodiment of this application further provides an encodingapparatus 7000. The encoding apparatus 7000 is configured to perform thedata transmission method shown in FIG. 4. The apparatus may beapplicable to the communications system shown in FIG. 3. A part or allof the data transmission method shown in FIG. 4 may be implemented byhardware, or may be implemented by software. When the data transmissionmethod is implemented by hardware, the encoding apparatus includes: aninput interface circuit 71, configured to obtain a bit sequence when alength of a mother code is N; a logic circuit 72, configured to generatea to-be-sent bit sequence; and an output interface circuit 73,configured to output the to-be-sent bit sequence, where the to-be-sentbit sequence includes one or more bits in a bit sequence having a lengthof (N−M), where N is the length of the mother code for polar encoding, Mis a length of encoded bits obtained after rate matching is performed ona bit sequence having a length of N, N is m raised to the power of aninteger, m is a positive integer greater than 1, M is a positiveinteger, and N<M.

Further, the to-be-sent bit sequence further includes:

one or more bits in the bit sequence having the length of N.

Further, when m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t), a lengthof the to-be-sent bit sequence is min (m{circumflex over ( )}(ceil(log_(m)M)+1), Nmax), where

P_(t) is a threshold of a quantity of punctured bits, and Nmax is amaximum length of the mother code.

Further, when N meets the following conditions: N/2−M≤P_(t), andN−M≥P_(t), a length of the to-be-sent bit sequence is min (m{circumflexover ( )}(ceil (log_(m)M)+1), Nmax), where

P_(t) is a threshold of a quantity of punctured bits, and Nmax is amaximum length of the mother code.

Further, the apparatus is a network device or a terminal device.

For functions performed by the logic circuit in the foregoing datatransmission apparatus, refer to the descriptions in the foregoingmethod embodiments. Details are not described herein again.

In one embodiment, the encoding apparatus may be a chip or an integratedcircuit.

In one embodiment, when some or all of the encoding methods in theforegoing embodiments are implemented by software, as shown in FIG. 8,an encoding apparatus 8000 includes: a memory 81, configured to store aprogram; and a processor 82, configured to execute the program stored inthe memory 81, where when the program is executed, the encodingapparatus is enabled to obtain a bit sequence when a length of a mothercode is N; generate a to-be-sent bit sequence; and output the to-be-sentbit sequence. The apparatus may be applicable to the communicationssystem shown in FIG. 3.

In one embodiment, the memory 81 may be a physically independent unit,or may be integrated together with the processor 82.

In one embodiment, when a part or all of the data transmission methodaccording to the foregoing embodiment in FIG. 4 is implemented bysoftware, the encoding apparatus 8000 may include only the processor 82.The memory 81 configured to store the program is located outside theencoding apparatus 8000, and the processor 82 is connected to the memory81 by using a circuit/wire, and is configured to read and execute theprogram stored in the memory 81.

The processor 82 may be a central processing unit (CPU), a networkprocessor (NP), or a combination of a CPU and an NP.

The processor 82 may further include a hardware chip. The hardware chipmay be an application-specific integrated circuit (ASIC), a programmablelogic device (PLD), or a combination thereof. The PLD may be a complexprogrammable logic device (CPLD), a field-programmable logic gate array(FPGA), a generic array logic (GAL), or any combination thereof.

The memory 81 may include a volatile memory, for example, a randomaccess memory (RAM). The memory 81 may alternatively include anon-volatile memory, for example, a flash memory, a hard disk drive(HDD), or a solid-state drive (SSD). The memory 81 may alternativelyinclude a combination of the foregoing types of memories.

FIG. 9 is a schematic flowchart of a decoding method according to anembodiment of this application. The method may include the followingoperations.

S91: Receive soft information corresponding to a bit sequence, where thesoft information includes soft information corresponding to one or morebits in a bit sequence having a length of (N−M), where N is a length ofa mother code for polar encoding, M is a length of encoded bits obtainedafter rate matching is performed on a bit sequence having a length of N,N is m raised to the power of an integer, m is a positive integergreater than 1, M is a positive integer, and N<M.

S92: Combine the soft information for decoding, to obtain decoded bits.

Further, the to-be-sent bit sequence further includes:

one or more bits in the bit sequence having the length of N.

During implementation, after a receive end receives an initiallytransmitted sequence and a retransmitted sequence, to combine softinformation received by the receive end, only a one-dimensional matrixy₁ ^(N) having a size of N is maintained, where an initial value of y₁^(N) is 0. Soft information received by the receive end each time isadded, based on a position of each bit in the mother code, to softinformation located at a corresponding position in y₁ ^(N). In oneembodiment, because rate matching, interleaving, buffering, and the likeneed to be performed during bit transmission, a position of each bit inthe mother code may not be aligned with a position in y₁ ^(N).Therefore, when receiving the initially transmitted sequence or theretransmitted sequence, the receive end needs to align a position of theinitially transmitted sequence or the retransmitted sequence in themother code with a position in y₁ ^(N). In one embodiment, assuming thatretransmitted soft information received from a channel is s₁ ^(M), softinformation in y₁ ^(N) is updated to y_(i)=y_(i)+s_(j), f(i)=j, where jis a position of a bit in s, and i is a position of a bit in y.Therefore, the receive end needs to reserve only a buffer having a sizeof a Seq. 2 for combining the soft information. For example, FIG. 10 isa schematic diagram of a process of combining soft information receivedby the receive end. As shown in FIG. 10, if a length of an initiallytransmitted sequence Seq. 0 is 16 and 4 bits are punctured, the receiveend needs to maintain a one-dimensional matrix y₁ ^(N) in which N=16,and an initial value of y₁ ^(N) is set to 0. When the initiallytransmitted sequence is received (that is, 1st received LLR for firsttransmission), a position of a bit in the Seq. 0 and a position of a bitin y₁ ^(N) are aligned, and the Seq. 0 is combined into y₁ ^(N). When aretransmitted sequence of the first time (2nd received LLR) and aretransmitted sequence of the second time (3rd received LLR) arereceived, a position of each bit in the retransmission sequence and aposition of a bit in y₁ ^(N) are aligned, and received retransmittedsequences are combined into y₁ ^(N). Alternatively, after the initiallytransmitted sequence and all retransmitted sequences are received, theinitially transmitted sequence and the all retransmitted sequences arecombined into y₁ ^(N).

According to a decoding method provided in this embodiment of thisapplication, an additional coding gain is generated during decoding, sothat a decoding FER is reduced, and decoding performance is improved.

Based on an inventive idea the same as the decoding method provided inthe foregoing embodiment, as shown in FIG. 11, an embodiment of thisapplication further provides a decoding apparatus 1100. The decodingapparatus 1100 may be configured to perform the decoding method providedin the embodiments of this application. The apparatus may be applicableto the communications system shown in FIG. 3. The decoding apparatus1100 includes:

a receiving module 111, configured to receive soft informationcorresponding to a bit sequence; and

a decoding module 112, configured to combine the soft information fordecoding, to obtain decoded bits.

Based on an inventive idea the same as the decoding method provided inthe foregoing embodiment, as shown in FIG. 12, an embodiment of thisapplication further provides a decoding apparatus 1200. The decodingapparatus 1200 is configured to perform the foregoing decoding method.The apparatus may be applicable to the communications system shown inFIG. 3. A part or all of the foregoing decoding method may beimplemented by hardware, or may be implemented by software. When a partor all of the foregoing decoding method is implemented by hardware, thedecoding apparatus 1200 includes: an input interface circuit 121,configured to receive soft information corresponding to a bit sequence;a logic circuit 1102, configured to perform the foregoing decodingmethod; and an output interface circuit 1103, configured to outputdecoded bits.

In one embodiment, the decoding apparatus 1200 may be a chip or anintegrated circuit.

In one embodiment, when a part or all of the decoding method in theforegoing embodiments are implemented by using software, as shown inFIG. 13, a decoding apparatus 1300 includes: a memory 131, configured tostore a program; and a processor 132, configured to execute the programstored in the memory 131, where when the program is executed, thedecoding apparatus 1300 is enabled to implement the decoding methodprovided in the foregoing embodiments.

In one embodiment, the memory 131 may be a physically independent unit,or may be integrated together with the processor 132.

In one embodiment, when a part or all of the decoding method of theforegoing embodiments are implemented by software, the decodingapparatus 1300 may alternatively include only the processor 132. Theapparatus may be applicable to the communications system shown in FIG.3. The memory 131 configured to store the program is located outside thedecoding apparatus 1300, and the processor 132 is connected to thememory 131 by using a circuit/wire, and is configured to read andexecute the program stored in the memory 131.

The processor 132 may be a central processing unit (CPU), a networkprocessor (NP), or a combination of a CPU and an NP.

The processor 132 may further include a hardware chip. The hardware chipmay be an application-specific integrated circuit (ASIC), a programmablelogic device (PLD), or a combination thereof. The PLD may be a complexprogrammable logic device (CPLD), a field-programmable logic gate array(FPGA), a generic array logic (GAL), or any combination thereof.

The memory 131 may include a volatile memory, for example, arandom-access memory (RAM). The memory 131 may alternatively include anon-volatile memory, for example, a flash memory, a hard disk drive(HDD), or a solid-state drive (SSD). The memory 131 may alternativelyinclude a combination of the foregoing types of memories.

An embodiment of this application further provides a network device.Referring to FIG. 14, the foregoing encoding apparatus and/or decodingapparatus may be installed in a network device 1400. The apparatus maybe applicable to the communications system shown in FIG. 3. In additionto the foregoing encoding apparatus and decoding apparatus, the networkdevice 1400 may further include a transceiver 142. A bit sequenceencoded by the encoding apparatus is subject to subsequent change orprocessing and then sent by the transceiver 142 to a terminal device, orthe transceiver 142 is further configured to receive information/datafrom the terminal device. The information/data is subject to a series ofprocessing and is converted into a to-be-decoded sequence, and theto-be-decoded sequence is processed by the decoding apparatus to obtaina decoded sequence. The network device 1400 may further include anetwork interface 144, configured to communicate with another networkdevice.

Similarly, as shown in FIG. 15, the foregoing encoding apparatus and/orthe decoding apparatus may be installed in a terminal device 1500. Theapparatus may be applicable to the communications system shown in FIG.3. In addition to the foregoing encoding apparatus and decodingapparatus, the terminal device 1500 may further include a transceiver152. A bit sequence encoded by the encoding apparatus is subject tosubsequent change or processing and then sent by the transceiver 152 toa network device, or the transceiver 152 is further configured toreceive information/data from the network device. The information/datais subject to a series of processing and is converted into ato-be-decoded sequence, and the to-be-decoded sequence is processed bythe decoding apparatus to obtain a decoded sequence. The terminal 1500may further include an input/output interface 154, configured to receiveinformation input by a user. Information that needs to be sent to thenetwork device needs to be processed by an encoder and then sent by thetransceiver 152 to the network device. After subject to subsequentprocessing, data decoded by a decoder may alternatively be presented tothe user by using the input/output interface 154.

An embodiment of this application further provides a computer storagemedium, storing a computer program. The computer program is configuredto perform the data transmission method shown in FIG. 4 and the decodingmethod provided in the foregoing embodiments.

An embodiment of this application further provides a polar code encodingapparatus, including any encoding apparatus in FIG. 7 to FIG. 9 and anydecoding apparatus in FIG. 11 to FIG. 13.

An embodiment of this application further provides a computer programproduct including an instruction. When the computer program product isrun on a computer, the computer is enabled to perform the datatransmission method shown in FIG. 4 and the decoding method provided inthe foregoing embodiments.

A person of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm operations may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of this application.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the foregoing described system, apparatus, and unit, refer toa corresponding process in the foregoing method embodiments, and detailsare not described herein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the foregoing describedapparatus embodiments are merely examples. For example, the unitdivision is merely logical function division and may be another divisionduring actual implementation. For example, a plurality of units orcomponents may be combined or integrated into another system, or somefeatures may be ignored or not performed. In addition, the displayed ordiscussed mutual coupling or direct coupling or communicationconnections may be implemented by using some interfaces. The indirectcoupling or communication connections between the apparatuses or unitsmay be implemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,that is, may be located in one position, or may be distributed on aplurality of network units. Some or all of the units may be selectedbased on actual requirements to achieve the objectives of the solutionsof the embodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units are integrated into one unit.

All or some of the foregoing embodiments may be implemented by usingsoftware, hardware, firmware, or any combination thereof. When softwareis used to implement the embodiments, the embodiments may be implementedcompletely or partially in a form of a computer program product. Thecomputer program product includes one or more computer instructions.When the computer program instructions are loaded and executed on thecomputer, the procedure or functions according to the embodiments ofthis application are all or partially generated. The computer may be ageneral-purpose computer, a dedicated computer, a computer network, orother programmable apparatuses. The computer instruction may be storedin a computer-readable storage medium, or may be transmitted by usingthe computer-readable storage medium. The computer instructions may betransmitted from a website, computer, server, or data center to anotherwebsite, computer, server, or data center in a wired (for example, acoaxial cable, an optical fiber, or a digital subscriber line (DSL)) orwireless (for example, infrared, radio, or microwave) manner. Thecomputer-readable storage medium may be any usable medium accessible bya computer, or a data storage device such as a server or a data center,integrating one or more usable media. The usable medium may be amagnetic medium (for example, a floppy disk, a hard disk, or a magnetictape), an optical medium (for example, a digital versatile disc (DVD), asemiconductor medium (for example, a solid-state drive (SSD)), or thelike.

A person of ordinary skill in the art may understand that all or some ofthe processes of the methods in the foregoing embodiments may beimplemented by a computer program instructing relevant hardware. Theprogram may be stored in a computer-readable storage medium. When theprogram runs, the processes of the methods in the embodiments areperformed. The foregoing storage medium includes: any medium that canstore program code, for example, a read-only memory (ROM), a randomaccess memory (RAM), a magnetic disk, or an optical disc.

What is claimed is:
 1. A data transmission method comprising: generatinga to-be-sent bit sequence, wherein the to-be-sent bit sequence comprisesone or more bits in a bit sequence having a length of (N−M), wherein Nis a length of a mother code for polar encoding, M is a length ofencoded bits obtained after rate matching is performed on a bit sequencehaving a length of N, N is m raised to the power of an integer, m is apositive integer greater than 1, M is a positive integer, and N<M; andsending the generated bit sequence.
 2. The method according to claim 1,wherein the to-be-sent bit sequence further comprises: one or more bitsin the bit sequence having the length of N.
 3. The method according toclaim 1, wherein when m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t), alength of the to-be-sent bit sequence is min (m{circumflex over( )}(ceil (log_(m)M)+1), Nmax), wherein, P_(t) is a threshold of aquantity of punctured bits, and Nmax is a maximum length of the mothercode.
 4. The method according to claim 1, wherein when N meets thefollowing conditions: N/2−M≤P_(t), and N−M≥P_(t), a length of theto-be-sent bit sequence is min (m{circumflex over ( )}(ceil(log_(m)M)+1), Nmax), wherein, P_(t) is a threshold of a quantity ofpunctured bits, and Nmax is a maximum length of the mother code.
 5. Adata transmission apparatus comprising: a processing module configuredto generate a to-be-sent bit sequence, wherein the to-be-sent bitsequence comprises one or more bits in a bit sequence having a length of(N−M), wherein N is a length of a mother code for polar encoding, M is alength of encoded bits obtained after rate matching is performed on abit sequence having a length of N, N is m raised to the power of aninteger, m is a positive integer greater than 1, M is a positiveinteger, and N<M; and a sending module configured to send the generatedbit sequence.
 6. The apparatus according to claim 5, wherein theto-be-sent bit sequence further comprises: one or more bits in the bitsequence having the length of N.
 7. The apparatus according to claim 5,wherein when m{circumflex over ( )}ceil (log_(m)M)−M<=P_(t), a length ofthe to-be-sent bit sequence is min (m{circumflex over ( )}(ceil(log_(m)M)+1), Nmax), wherein P_(t) is a threshold of a quantity ofpunctured bits, and Nmax is a maximum length of the mother code.
 8. Theapparatus according to claim 5, wherein when N meets the followingconditions: N/2−M≤P_(t), and N−M≥P_(t), a length of the to-be-sent bitsequence is min (m{circumflex over ( )}(ceil (log_(m)M)+1), Nmax),wherein, P_(t) is a threshold of a quantity of punctured bits, and Nmaxis a maximum length of the mother code.
 9. The apparatus according toclaim 5, wherein the apparatus is a network device or a terminal device.10. An encoding apparatus comprising: a processor configured to:generate a to-be-sent bit sequence, wherein the to-be-sent bit sequencecomprises one or more bits in a bit sequence having a length of (N−M),wherein N is a length of a mother code for polar encoding, M is a lengthof encoded bits obtained after rate matching is performed on a bitsequence having a length of N, N is m raised to the power of an integer,m is a positive integer greater than 1, M is a positive integer, andN<M.
 11. The apparatus according to claim 10, wherein the to-be-sent bitsequence further comprises: one or more bits in the bit sequence havingthe length of N.
 12. The apparatus according to claim 10, wherein whenm{circumflex over ( )}ceil (log_(m)M)−M<=P_(t), a length of theto-be-sent bit sequence is min (m{circumflex over ( )}(ceil(log_(m)M)+1), Nmax), wherein, P_(t) is a threshold of a quantity ofpunctured bits, and Nmax is a maximum length of the mother code.
 13. Theapparatus according to claim 10, wherein when N meets the followingconditions: N/2−M≤P_(t), and N−M≥P_(t), a length of the to-be-sent bitsequence is min (m{circumflex over ( )}(ceil (log_(m)M)+1), Nmax),wherein, P_(t) is a threshold of a quantity of punctured bits, and Nmaxis a maximum length of the mother code.
 14. The apparatus according toclaim 10, wherein the apparatus further comprises a memory, and thememory is configured to store a program instruction to be implemented bythe processor to generate the to-be-sent bit sequence.
 15. The apparatusaccording to claim 10, wherein the apparatus is a network device or aterminal device.